Mike,
I spent about two weeks with a boot maker in Oklahoma last year. She and I made a pair of boots while I was in her shop, so I wanted to let you know I have one pair of boots under my belt, and she helped me a great deal of course. So take this for what it is worth.
We stacked the heel each layer at a time. We used permanent glue then nailed wooden pegs into each layer. You have to pay attention to where you put the pegs so you don't put them on top of each other. Most high end boot makers, the the lady that taught me is one, refuse to use any nails with their boots. The only exception to that is for the nails that you put the heel pad on with. The rest is done with wooden pegs.
Hope that helps.
Kevin